There are numerous applications of electrical limit switches on machinery having moving components. It is customary to mount a limit switch or switches adjustably relative to moving machine carriages or like parts whose extent of movement, stopping or reversal of movement, must be accurately regulated.
A typical application of electrical limit switches is disclosed in United States application S.N. 273,866, filed July 21, 1972, now U.S. Pat. No. 3,803,824, issued Apr. 16, 1974. In this patent a mechanical spinning frame ring rail lowering mechanism is disclosed consisting of a mechanical clutch and pulley arrangement, whereby activation of the clutch at a certain time during the winding of textile bobbins will cause the ring rail to be lowered to a bobbin doffing position and held in such position prior to the next bobbin building cycle of operation.
In conjunction with the clutch unit, a clutch-activating or trip mechanism is bodily mounted on the ring rail to move therewith and the purpose of the trip mechanism is to cause the release at the proper time of a spring-loaded linkage which is connected to a rotary activating tab of the clutch, whereby release of the linkage by the trip mechanism will allow the linkage to activate the clutch for lowering the ring rail. More particularly, the coasting inertia of the spining frame is employed, following the activation of the clutch to effect the lowering of the ring rail, the spinning frame motor being de-activated according to one disclosed mode of operation when the linkage is released by the trip mechanism.
As disclosed in said patent, the trip mechanism on the oscillating ring rail includes a release finger which engages the linkage on the next-to-last upstroke of the ring rail to cause the release of a trip element, which on the final upstroke of the ring rail engages and releases the clutch activating linkage.
The patented system discloses two alternate modes of operation, the first of which involves a single switch to shut off the spinning frame motor as the ring rail lowering clutch unit is activated. This mode depends upon the coasting of the frame to completely lower the ring rail. In the alternate mode of operation, two separate switches are employed and the spinning frame motor is not shut off until both electrical switches have been operated.
While the present invention has an almost limitless range of utility in connection with machinery, it is ideally suited for use in the system covered by the above-mentioned patent and therefore will be disclosed in connection therewith. It should be understood, however, that the invention is in no sense limited to this particular use or application.